The present invention relates to a vacuum cleaner filter assembly; more particularly, to such an assembly having two stages of filtration and utilizing a paper filter bag which is less sensitive to clogging of the pores of the same.
In the prior vacuum cleaner art, it is customary to direct dirt entrained air directly into a filter bag fabricated from an air permeable material so that the dirt may be captured therein and the air exhausted through the pores of the filter material to the ambient. Normally, the clogging of the pores of the filter material was known to take place but had not been a problem since sufficient opening exists for air to be exhausted from the filter bag through the remaining pores. However, certain materials have been noted to have an especially severe effect in clogging the pores of paper filter material. Among these certain materials are some dry chemical carpet cleaning powders.
What is required is a filter bag usable to pick up these dry chemical carpet cleaning powders which is not sensitive to the pore clogging capability of these powders.